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Published in Joseph Kovi, Hung Dinh Duong, Frozen Section In Surgical Pathology: An Atlas, 2019
The thymus is essentially a lymphoepithelial organ. It is surrounded by a delicate fibrous capsule which sends slender septa into the lymphoepithelial parenchyma dividing the organ into several lobules. Each lobule consists of an outer lymphocyte rich, strongly hematoxylinophilic cortex, and a lightly stained medulla. The epithelial cells form peculiar spheres in the medulla, the so-called “Hassall’s corpuscles.”
Neurocutaneous Syndromes With Interstitial Lung Disease
Published in Lourdes R. Laraya-Cuasay, Walter T. Hughes, Interstitial Lung Diseases in Children, 2019
The author has managed two patients with AT. One was a 17-year-old male who developed pneumothorax and who subsequently died from chronic respiratory failure. Reticuloendoth-eliosis was diagnosed from a pulmonary biopsy. His sister also died from the malignant complication of AT during late adolescence. The other patient was a 14-year-old female whose major postmortem findings were acute and diffuse interstitial pneumonitis superimposed on diffuse pulmonary fibrosis with evidence of cor pulmonale. No ovaries were identifiable. Thymic tissue showed absence of Hassall’s corpuscles and was very hypoplastic. Lymphoid tissue was hypoplastic.
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Published in Thomas Hester, Iain MacGarrow, Surgical SBAs for Finals with Explanatory Answers, 2018
In neonates the thymus is responsible for the development of T lymphocytes; in the adult it becomes a fat infiltrated remnant. Myasthenia gravis is an autoimmune disorder of peripheral nerves in which antibodies form against acetylcholine (ACh) postsynaptic receptors. Cholinergic nerve conduction to striated muscle is impaired by both mechanical blockage of the binding site by antibodies and by destruction of the postsynaptic receptor. Patients become symptomatic once the number of ACh receptors is reduced to approx. 30%. The earliest muscles involved are often those of the eyelids, those controlling eye movements and muscles controlling swallowing and speech. About 10% of cases are associated with a tumour of the thymus and most of the rest have thymic hyperplasia; the mechanism of the link revolves around T cell development, though is not fully understood presently. The thymus contains cells called Hassall’s corpuscles.
Advances in understanding of Netherton syndrome and therapeutic implications
Published in Expert Opinion on Orphan Drugs, 2020
Evgeniya Petrova, Alain Hovnanian
Different immunological abnormalities have been reported in NS patients with variable consistency. Blood eosinophilia is often observed with various abnormalities in T and B lymphocyte counts and/or subpopulations. Immunophenotyping of a limited number of NS patients showed no evidence of immune deficiency, but some T and B cell imbalances in NS children and a Th17/Th22 bias, with no signs of Th2 skewing [16–18]. NK cell function was reported to be reduced in two studies [16,19]. Plasmablasts were found to be decreased in one study [16]. Total IgG, IgA and IgM are most often normal or sometimes raised. Total serum IgE levels are almost always significantly enhanced with increased specific IgE against food and airborne allergens. LEKTI being expressed in the Hassall’s corpuscles of the thymus, it is possible that T cell differentiation is altered. However, except for increased serum IgE levels, immune abnormalities in NS are inconstant. It is therefore also possible that these abnormalities are secondary to chronic skin infections and inflammation. Further phenotyping and functional studies of lymphocyte subclasses in a sufficient number of NS patients by age category are required.
Growth hormone enhances the CD34+ stem cells repopulation of the male albino rat thymus gland in cyclophosphamide induced injury: immunohistochemical and electron microscopic study
Published in Ultrastructural Pathology, 2023
Amira I. Shrief, Walaa H.E. Hamed, Shireen A Mazroa, Amal M. Moustafa
In the current work, there was an increase in the size and the number of Hassall’s corpuscles in CP-treated rats (group ІІ). Similar finding was reported by other authors.22 It has been reported that the corpuscles are generally increased in number throughout degenerative involution and early regeneration, but again reduced to about the normal level with structural recovery of thymus gland. It could be attributed to the role of Hassall’s corpuscles in removing apoptotic thymocytes.23
Thymic and Peripheral T-cell Polarization in an Experimental Model of Russell’s Viper Venom-induced Acute Kidney Injury
Published in Immunological Investigations, 2022
Sreyasi Das, Farhat Nasim, Roshnara Mishra, Raghwendra Mishra
Thymus, a primary lymphoid organ, is often ignored in adult studies due to age related involution. It is the major site of T cell development where progenitor cells pass through a series of differentiation stages to form functional naive T cells repertoire through tightly regulated positive and negative selection method which includes, but is not limited to, clonal deletion and clonal diversion (Xing and Hogquist 2012). Anatomically thymus is divided into two parts, the outer cortex where T-cell differentiation takes place, and the inner medulla, where newly formed T-cells colonize and undergo maturation for final seeding into the peripheral organs (Belizário et al. 2016). Histologically, the cortex is characterized as darkly stained outer region of the thymus with densely packed immature lymphocytes, epithelial cells and macrophages. The central part of each follicle is called medulla is comparatively more eosinophilic and containing fewer lymphocytes but plenty of epithelial cells. Hassall’s corpuscles, a collection of hypertrophied keratinized concentric thymic epithelial reticular cells, are a distinctive feature of thymic medulla (Pearse 2006 and further details therein).The thymic cortical and medullary microenvironment play a crucial role in the process of differentiation of T cells in CD4+ single positive helper T cells (TH) and CD8+ single positive cytotoxic T cells (TC) and their respective subsets through a series of transformations through CD4− CD8− double negative (DN) subsets (based on CD44 and CD25 expression level) and CD4+ CD8+ double positive (DP) stage, which emigrates to different tissue and peripheral blood pool for maintenance of immune homeostasis and response (Aghaallaei and Bajoghli 2018; Lins et al. 2020; Pearse 2006). Recent findings suggest that thymus of adult mammals, despite age-related involution, actively participates in different pathophysiological conditions (den Braber et al. 2012; Haynes et al. 2000)